Abstract

Naturally occurring elongate bodies that are segmented or appear to be in the process of segmentation occur in a variety of environments and scales. A simple, process-based numerical model of planform shoreline evolution demonstrates that fetch controls on alongshore sediment transport can result in the segmentation of an elongate water body into smaller, rounded lakes or ponds. The shape of elongate water bodies leaves their long coasts prone to a high-angle-wave instability in shoreline shape that results in the formation of capes that grow through interactions with one another along the same coast. In a numerical model, as capes extend farther offshore, a new behavior emerges, whereby capes on opposing coasts attract one another laterally as they grow, suggesting a novel mechanism for large-scale shoreline self-organization through fetch-limiting interactions. We demonstrate these interactions through analysis of local net sediment flux and coastline stability. Ensemble model runs suggest that, for a symmetric wind distribution, the initial segmentation of a water body requires four lengths per initial width, yet water bodies with higher initial aspect ratios segment to one final round water body per factor of two of the initial aspect ratio. Wave-dominated elongate water bodies with coasts consisting of clastic sediment (and a lack of vegetation) are most likely to undergo this predicted segmentation.